One prior-art power microwave hybrid integrated circuit is known, the circuit comprises a metal base having through holes for naked semiconductor chips and an insulating polymer film joined to the metal base and having through holes mating with those of the base. A second insulating film is placed on and held to the first insulating film, said second film having through holes of a smaller size mating with the holes in the first polymer film. The naked semiconductor chips are mounted on the back side of the second polymer film with their bonding pads towards the films (i.e., upwards). A second commutation level is arranged on the face side of the second polymer film and is electrically connected to the chip bonding pads through the holes in the second polymer film (JP, B. 57-036746).
The integrated circuit discussed above is possessed of a low heat dissipation rate due to a small chip-to-metal base heat contact area.
One more prior-art power microwave hybrid integrated circuit is known, the circuit comprises a metal base having recesses, naked semiconductor chips disposed in and fixed to said recesses with a binder, a dielectric multilayer board having a topological metallization pattern on its face side and through holes electrically connecting the chip bonding pads to the topological metallization pattern of the board and filled with an electrically conducting material. The chips are slightly sunk into the metal base, and the planarization of the circuit is attained by applying, polymer dielectric layers of the board (cf. "Electronic devices on chip integral circuits", edited by I. N. Vozhenin, 1985, "Radio i Sviaz" Publishers, Moscow, p.261 (in Russian).
The circuit mentioned above is possessed of an inadequate heat conductance and low electrical characteristics.